WEDNESDAY, Nov. 8, 2017 (HealthDay News) -- The brain gets priority over muscles when both are competing for energy, a new study finds.

Tests with 62 elite rowers at a British university, who averaged 21 years old, revealed that when they had to think fast and exert themselves at the same time, the brain was first in line to receive energy-providing glucose.

This is likely an evolutionary trait because quick thinking rather than fast moving may have helped human ancestors survive, according to researchers from the University of Cambridge.

"The development of an enlarged and elaborated brain is considered a defining characteristic of human evolution, but one that has come as a result of trade-offs," study lead author Danny Longman, from the archaeology department, said in a university news release.

"At the evolutionary level, our brains have arguably cost us decreased investment in muscle as well as a shrunken digestive system," he said.

"The selfish nature of the brain has been observed in the unique preservation of brain mass as bodies waste away in people suffering from long-term malnutrition or starvation, as well as in children born with growth restriction," Longman added.